The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Catalytic converters are used with internal combustion engines to reduce emissions. The catalytic converters generally operate more efficiently at elevated temperatures. When an engine is started, the catalytic converter may not be efficient in removing emissions from the exhaust gas until the catalytic converter reaches an operating temperature (e.g., a “light-off temperature”). The light-off temperature may be a temperature where the conversion of carbon monoxide (CO), unburned hydrocarbons (HC), and nitride oxides (NOx) has reached 50% efficiency.
During engine cold start, a rich fuel air mixture may be supplied to the engine to increase the exhaust temperature and the exhaust gas may be used to heat the catalytic converter. Therefore, the engine is not operated in a fuel-efficient manner during engine start. An electrically heated catalyst (EHC) may be activated during engine start to provide extra heat to the catalytic converter. The EHC, however, has a slow response and may not be able to quickly heat the catalytic converter as desired.